1. Field of the Invention
The present invention relates to an electric stapler, and more particularly, to an electric stapler in which a clincher and a driver are separated from each other and arranged in a vertical direction.
2. Description of the Related Art
FIG. 4 shows an electric stapler adapted to be incorporated mainly in a copying machine. A clincher unit 1 and a driver unit 2 are vertically separated from each other in order to bind a document at its center portion. The clincher unit 1 is fixed to an upper base plate 3, and the driver unit 2 is fixed to a lower base plate 4 which is arranged in parallel to the upper base plate 3 spaced therefrom.
Into a clincher guide 5 formed in a vertical direction in a front part (a left side in the drawing) of the clincher unit 1, a clincher sleeve 6 and a clincher 7 are inserted. The clincher sleeve 6 and the clincher 7 are driven to move up and down by means of a motor 8, a reduction gear train 9, cam levers 10 at left and right sides (in a direction of Z axis in the drawing), and a central cam lever 11.
When the motor 8 is energized, the cam levers 10 at the left and right sides, which are engaged with an eccentric roller 12 attached to a final reduction gear 9a, move upward and downward about a shaft 13 as a pivotal axis. The clincher sleeve 6 and the clincher 7, which are engaged in elongated holes in front parts of the cam levers 10, perform one cycle of a reciprocating motion in which they move upward to return to the standby position after they have moved downward from a standby position. On this occasion, after the clincher sleeve 6 has come into contact with sheets of paper to discontinue the downward movement, the central cam lever 11 further pushes down the clincher 7, and the clincher 7 bends legs of the staple which has entered in the clincher sleeve 6, into a flat shape.
The driver unit 2 is so designed that its front part freely moves up and down within a determined range about a shaft 14 in its rear part as a pivotal axis, and is urged to an elevated position by means of a compression spring 15. Into a driver guide 16 in the front part of the driver unit 2, a driver plate 17 and a forming plate 18 are inserted in an overlapped manner. A lower end of the driver plate 17 is in contact with a stopper 19 provided on a frame of the stapler. Numeral 20 designates a staple cartridge. A staple sheet S to which a number of straight staples are bonded in parallel is loaded in the staple cartridge 20.
FIG. 5 shows the electric stapler in operation. When the clincher sleeve 6 and the clincher 7 move downward to push down the front part of the driver unit 2, other parts than the driver plate 17 and the forming plate 18 which are in contact with the stopper 19 rotate downward. With this rotation, the driver plate 17 is projected upward from the driver unit 2. A staple in a foremost row inside the driver guide 16 is pushed upward and clamped by means of the clincher sleeve 6 and the clincher 7 to pass through the document (not shown), and both left and right legs of the staple are bent inwardly by means of the clincher 7. At the same time, a staple in the next row of the ejected staple is formed by the forming plate 18 into a bent shape like a gate.
As described above, the conventional electric stapler has such a structure that the clincher sleeve 6 slides downward rectilinearly to push the driver unit 2, and the driver unit 2 rotates downwardly about the shaft 14 as the pivotal axis. Accordingly, when the document has been clamped between the clincher sleeve 6 and the driver unit 2, an angle of the driver plate 17 and an ejection angle of the staple may change according to thickness of the document. For this reason, the clincher sleeve 6 must be accurately aligned with the driver plate 17 so as to follow a change of the angle of the driver plate 17. Even a minor error in the alignment may result in distortion or clogging of the staples, and there has been a problem that high accuracy is required with respect to precision of the components and assembling work, and assembling adjustment is also difficult.
Therefore, there has arisen a technical problem to be solved for stabilizing the stapling that the clincher and the driver plate must be arranged so as to face with each other at a constant angle regardless of thickness of the document to be bound. An object of the present invention is to solve the above described problem.
This invention has been made in order to attain the above described object and to provide a electric stapler for binding a document inserted between a driver unit and a clincher unit, the electric stapler comprising the driver unit including a driver plate adapted to eject staples and a staple cartridge, and the clincher unit including a clincher adapted to bend legs of each of the staples which have been ejected and a clincher driving mechanism, wherein the driver unit and the clincher unit are separated from each other and arranged in a vertical direction. The electric stapler is characterized in that the driver unit is composed of a cartridge holder fixed to a frame of the electric stapler, said staple cartridge mounted to the cartridge holder so as to freely slide up and down, a spring for urging the staple cartridge toward the clincher unit opposed thereto, and the driver plate incorporated in the cartridge holder, the clincher of the clincher unit being so constructed as to push the staple cartridge to slide, whereby the staples in the staple cartridge are ejected by means of a driver in the cartridge holder.